1. Field of the Invention
The present invention relates to intermediates for the synthesis of o-sulfonamidophenol derivatives useful as dye releasing redox compounds (abbreviated as DRR compounds hereinafter) and o-aminophenol derivatives useful as developing agents, both of which can be employed in color photography. More particularly, it is concerned with intermediates for the synthesis of o-sulfonamidophenol derivatives which release diffusible dyes by a redox reaction resulting from development processing of a silver halide.
2. Development of the Invention
In U.S. Pat. No. 4,076,529 there is described a color diffusion transfer color image forming process using DRR compounds. The term "DRR compound" as used therein means a p-sulfonamidophenol (or a p-sulfonamidonaphthol) compound in which a non-diffusible phenolic group (or naphtholic group) is bonded to a dye moiety via a sulfonamido group at its p-position.
However, our research found that the above-described p-sulfonamidophenols provide a sufficiently high density for a transferred image only with difficulty. Moreover, since the above-described p-sulfonamidonaphthols leave p-naphthoquinones in areas of a light-sensitive element and cause yellow stains even though the light-sensitive element has been submitted to desilvering processing after dye release, it is impossible to utilize the color image remaining on such areas of the light-sensitive element as negative or positive image.
In Japanese Patent Application (OPI) No. 113624/76, o-sulfonamidophenols substituted by alkoxyl groups at the 4-position(s) are described as DRR compounds. These compounds possess rather good properties, compared with conventional DRR compounds, but they need to be further improved in dye releasing ability.
In addition, o-sulfonamidophenols having alkoxyl groups and methyl groups at their 5- and 4-positions, respectively, are described as DRR compounds in Japanese Patent Application (OPI) No. 149328/78. However, further improvement upon the dye releasing ability is required of these o-sulfonamidophenols also.